More Cryptosporidium Found In Bull Run Water

Photo: Centers for Disease Control

The Portland Water Bureau received additional results from ongoing monitoring from the Bull Run Watershed intake for Cryptosporidium, a potentially disease-causing microorganism. Between Oct. 29 and Nov. 1, two oocysts were detected from 50-liters of water collected on Sunday Oct. 29. No additional Cryptosporidium was detected from the 150-liters sampled Monday Oct. 30 through Wednesday Nov. 1. 

Prior to these detections, Cryptosporidium was last detected on Tuesday, Oct. 24 when two oocysts were detected from 50 liters of water from the Bull Run. The bureau continues to use the Bull Run as its primary source of drinking water. 

Exposure to Cryptosporidium can cause cryptosporidiosis, a serious illness. Symptoms can include diarrhea, vomiting, fever and stomach pain. People with healthy immune systems recover without medical treatment. According to the Center for Disease Control (CDC), people with severely weakened immune systems are at risk for more serious disease. Symptoms may be more severe and could lead to serious or life-threatening illness. Examples of people with weakened immune systems include those with AIDS; those with inherited diseases that affect the immune system; and cancer and transplant patients who are taking certain immunosuppressive drugs. 

EPA has estimated that a small percentage of the population could experience gastro-intestinal illness from Cryptosporidium and advises that customers who are immunocompromised and receive their drinking water from the Bull Run Watershed consult with their healthcare professional about the safety of drinking the tap water. The Portland Water Bureau and Burlington, City of Gresham, City of Sandy, City of Tualatin, Green Valley, GNR, Hideaway Hills, Lake Grove, Lorna Portland Water, Lusted, Palatine Hill, Pleasant Home, Raleigh, Rockwood, Skyview Acres, Tualatin Valley, Two Rivers, Valley View and West Slope Water Districts receive all or part of their drinking water supply from the Bull Run. To learn if your drinking water comes from Bull Run, please contact your local drinking water provider. 

Public health surveillance during and after a similar series of low-level detections from January through March of this year did not see an increase in Cryptosporidium-related illness. The general public is not advised to take additional precautions. 

The public and the media are encouraged to view all sampling results posted to the 

City's website at The media will also 

be notified of any further low-level detections on at least a weekly basis, if they occur. The 

bureau will notify the media and public immediately should further test results 

indicate a risk to public health and precautions are necessary. 

Customers with questions regarding water quality can call the Water Line at 



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